Portable electronic devices such as mobile phones, smart phones, personal digital assistants (PDAs), and tablets have become popular and ubiquitous. These devices typically include an electronic display screen, various user interface input components (such as touch screens, keypads, buttons, etc.), and a housing enclosing various electrical components. The color of the housing can provide aesthetic appeal, and various housing covers having different colors and different graphics designs are also often available to further personalize the device. In addition, the electronic display screen and the user interface input components can utilize white or colored backlights to enhance visibility and provide another source of aesthetic appeal.
When the electronic display screen is active (and backlight is on), the displayed graphics can be illuminated to a desired color or pattern, such as a color or pattern that matches the housing color or graphic pattern. When the electronic display screen is not active (the backlight is off or the pixels are controlled to be all dark), a black or grayish appearance is typically seen, which may not be particularly aesthetically appealing when considering the coloring of the rest of the mobile device.
Cholesteric liquid crystal (ChLC) panels have also been used to provide various color effects for electronic devices. These panels can be controlled to change along a spectrum of transparent and colored states, and generally require low power. However, they require a completely absorbing background (such as a black background) to achieve appropriate color, because without such a background, any light reflected from the panel surface will wash out the cholesteric layers, reducing contrast and color saturation. Typically, such a black background is achieved by printing or painting the underlying surface black. On an electronic device, this limits the area available for achieving cholesteric-based color effects, because such black backgrounds have not been possible over an electronic display or back lighted electronic keypad. Thus, there is an opportunity to achieve color effects over a greater area of an electronic device.